1. Field of the Invention
The present invention relates to a portable wireless electrical charging system.
2. Description of the Prior Art
Science and technology are developing very rapidly in current society, and with the rapid development in electronic technology, more and more people use various portable electronic devices in work and life, and in order to enhance the extensiveness of the application of portable electronic equipment, the need for charging systems for the electronic devices is thereby increased.
Ever since the phenomenon of electromagnetic induction was revealed by scientists, electric energy has been transferred mainly through direct contact of the wires. Charging of electronic equipment has always been conducted through the plug and socket, and to accomplish wireless power supply without conductor contact between the power supply system and the electronic equipment has become a focus of research, particularly for charging and supplying power to high-power loads. The idea of wireless power transmission was put forth long ago, but was considered by many scientists to be impossible to accomplish. Because the electromagnetic energy sent from the transmitter is scattered and transmitted around, humans lack the capability for centralized control of the electromagnetic energy, let alone utilization of it. In November 2006 , Marin Soljacic, an assistant professor in the Department of Physics, Massachusetts Institute of Technology (MIT) in the United States, put forward a new theory of utilizing electromagnetic energy through the technology of wireless electric power transmission. According to Soljacic's theory, so long as there is resonance generated between the electromagnetic transmitter and the receiving equipment in the same frequency, energy will be exchanged between them. The team led by him conducted experiments on this theoretical basis. Two copper wire coils were used as the resonator, with one coil connected with the power supply, as the transmitter; while the other in contact with a table lamp, was the receiver. As a result, they successfully lit a 60-watt electric lamp 2.13 m from the transmitter. However, the electromagnetic resonance coil is huge, and the two coils were required to be placed in a relatively fixed position. Furthermore, the transmission power was only 60 watts, the transmission efficiency of the electric energy was only 40% or so, and there was certain electromagnetic irradiation; therefore, it was only in a trial phase, and could not be promoted in a large area.
The drawbacks in the technology of wired power transmission and the technology of electric charging have affected development of social economy, and there is an urgent need to solve the problems mentioned above.
The technology of wireless charging originates from the technology of wireless electric transmission, transferring energy in the air between the charger and the device using magnetic resonance, with the coil and the capacitor forming resonance between the charger and the equipment, to accomplish the technology of highly efficient transmission of electric energy.
Because the transmission of the energy is based on near-field magnetic resonance, therefore the coil of the receiving end should receive as much as possible of the magnetic field sent out from the transmitting end. Correspondingly, every effort should be made to accomplish the following three objectives:
1. Because the strength of the magnetic field is inversely proportional to the distance from the transmitting end, the coil of the receiving end should be as close as possible to the transmitting end;
2. Because the magnetic flux plane of the coil is the largest at the transmitting end, the coil of the receiving end should be as parallel as possible with the plane of the coil of the transmitting end;
3. Because the magnetic field is strongest in the center of the coil of the transmitting end, the coil of the receiving end should be aligned as much as possible with the center of the coil of the transmitting end.
In recent years, experts in the field of wireless charging have attempted to use a no-automatic-alignment technology, a charging dock+rechargeable device mechanical structure alignment solution, and a charging dock+rechargeable device magnetic alignment solution.
As used herein, the terms “transmitting end” or “transmitter” mean the location or component from which electromagnetic charging energy is transmitted or emitted, and the terms “receiving end” or “receiver” mean the location or component where electrical charge is provided to a device to charge the device.
The no-automatic-alignment solution has a transmitting end that is essentially provided in the form of a plate, and where the coil of the transmitting end is inlaid inside the plate. The receiving end is placed directly on the plate of the transmitting end. This is the most common solution, and has the advantage is that it is simple. Unfortunately, this solution suffers from the disadvantage that if the device to be charged is not aligned properly, charging efficiency will be affected or, in the worst case, charging becomes absolutely impossible.
The charging dock +rechargeable device mechanical structure alignment solution is one where the transmitting end is a snap structure, and the coil of the transmitting end is inlaid inside the charging dock. The receiving end is mechanically snapped into position and fixed on the charging dock of the transmitting end. Such a solution is used for charging cordless toothbrushes and razors. The advantages of this solution are accurate positioning and fixing. The disadvantage is that the wireless transmission power is too low, which directly results in long charging times.
The charging dock+rechargeable device magnetic alignment solution is similar to the no-automatic-alignment solution, but where the magnet is placed in the center of the platform transmitting coil of the transmitting end. A corresponding magnet of polarity attraction is also placed in the center of the receiving coil of the loaded one. When the two magnets are close enough, they are accurately drawn together and aligned through magnetic attraction of the magnets. The advantage of this solution is accuracy in positioning and fixing. Further, when the transmitting end and the receiving end are close enough, the two will be drawn together and aligned with each other automatically. The disadvantage is that the receiving end must be placed on the charging plate during charging, and the entire charging system cannot be moved. Therefore, this solution is not good for mobile uses.
In short, for these three solutions, there is no guarantee of good transmission conditions from the transmitting end to the receiving end, the transmission power is lower, and the entire system cannot be moved during use.